Enzymes in Physiology Flashcards

1
Q

Why are enzymes important for pharmacy?

A
Involved in biochemical reactions
Reactions needed for survival
* component of pharmaceutical management of disease in patients
Used diagnostically
Used therapeutically
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2
Q

What are functions of enzymes?

A
Weaken bonds in reactions
May provide nucleophiles
Biological catalyst
Active site
Provide suitable environment 
Position reactants correctly 
May provide acid/base catalyst
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3
Q

What does enzymes NOT change?

A

Eqm position

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4
Q

What is an active site?

A

Region within enzyme that fits the shape of substrate molecules

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5
Q

What happens when enzyme and substrate bind?

A
Amino acid side chains align to bind to substrate through H-bonding
Products released (no longer fit active site)
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6
Q

Describe lock + key model

A

Rigid active site
Fit between active site + substrate = exact
Enzyme-substrate complex formed
Product different shape to substrate
Enzyme free to bind to another substrate when product released

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7
Q

Describe induced fit

A

Active site flexible + can change
Shape of enzyme, active site + substrate adjust to fit
Changed environment = improved catalysis
Greater range of substrate specificity

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8
Q

What is optimum pH?

A

7.4

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9
Q

What happens to enzyme activity at high/low pH?

A

Activity lost

= tertiary structure changes

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10
Q

What are exceptions to optimum pH?

A
Pepsin
Urease
Sucrase
Amylase
Trypsin
Arginase
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11
Q

What is pepsin pH?

A

2

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12
Q

What is urease pH?

A

5

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13
Q

What is sucrase pH?

A

6.2

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14
Q

What is amylase pH?

A

7

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15
Q

What is trypsin pH?

A

8

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16
Q

What is arginase pH?

A

9.7

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17
Q

What does changing pH alter?

A

Ionisation state of amino acid side chains

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18
Q

What is optimum temp?

A

37 degrees

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19
Q

Why is little activity at low temp?

A

Little KE

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20
Q

Why is little activity at high temp?

A

Denaturation

21
Q

What are cofactors?

A

Bind to enzyme to maintain correct configuration of active site
Metal ions or other inorganic factors

22
Q

Describe coenzyme

A

Required by some enzymes
Most carry e-
Many have modified vitamins in structure

23
Q

What is a coenzyme?

A

An organic molecule bound to enzyme by weak interactions/H bonds

24
Q

What do oxidoreductases do?

A

Catalyse transfer of e- from donors to acceptors

25
Q

What is an example of an oxidoreductase?

A

Dehydrogenase accept + donate e- as hydride ions

26
Q

What do transferases do?

A

Catalyse transfer of specific functional groups between molecules

27
Q

What is an example of a transferase?

A

Glycosyltransferase transfers carbohydrate residues

28
Q

What do hydrolases do?

A

Catalyse cleavage of bonds by addition of H2O molecules

29
Q

What is an example of hydrolase?

A

Lipases hydrolyse ester bonds

30
Q

What do lyases do?

A

Catalyse addition of H2O, NH3 or CO2 double bonds or remove them to create double bonds
Cleave bonds by means other than hydrolysis or oxidation

31
Q

What is an example of lyase?

A

Decarboxylase remove CO2

32
Q

What do isomerases do?

A

Catalyse interconversion of isomeric forms of a molecule by transferring groups within the same molecule

33
Q

What is an example of isomerase?

A

Conversion of Cis + Trans isomers

Conversion of D + L isomers

34
Q

What do ligases do?

A

Catalyse synthesis of new covalent bonds using ATP

35
Q

What is an example of a ligase?

A

Synthetases

36
Q

What can enzymes catalyse?

A

Single substrate
Group of substrates
Particular type of bond

37
Q

What is an absolute enzyme catalysis ?

A

Catalyses one type of reaction for a single substrate

38
Q

What is a group enzyme catalysis?

A

Catalyses one type of reaction for similar substrates

39
Q

What is a linkage group catalysis?

A

Catalyses one type of reaction for specific type of bond

40
Q

What does active site conformation drive?

A

Selectivity

41
Q

What does chymotrypsin prefer?

A

Aromatic side chains adjacent to scissile bond

42
Q

What does trypsin prefer?

A

Positively charged side chains that can interact with ASP189

43
Q

What does elastase prefer?

A

Small uncharged side chains, as pocket blocked

44
Q

What are isoenzymes?

A

Different forms of an enzyme catalysing same reaction in different tissues

45
Q

What are the difference between isoenzymes?

A

Slight variations in sequences of subunits in quaternary structure
Can have different attributes + optimal conditions

46
Q

Describe allosteric regulation of enzyme action

non-competitive inhibition

A

Effector molecules change activity of enzyme by binding to 2nd site

47
Q

What is positive allosterification?

A

Speed up enzyme activity

48
Q

What is negative allosterification?

A

Slow enzyme action

49
Q

What is feedback inhibition?

A

Product late in series of enzyme-catalysed reactions serves as an inhibitor for previous allosteric enzyme earlier in series